Tuesday, February 12, 2013

Mild Traumatic Brain Injury Linked to Brain ‘Potholes'

A recent study has found that U.S. soldiers returning from Iraq and Afghanistan with mild traumatic brain injury (TBI) have measurable abnormalities in the white matter of their brains — described by scientists as “potholes.”According to psychiatrists with University of Iowa Health Care, TBI — including concussions — is one of the most common types of neurological disorder, affecting approximately 1.3 million Americans annually. It has received more attention recently because of its impact on two groups of patients: professional athletes, especially football players; and soldiers returning from war with blast-related TBI.It is estimated that 10 to 20 percent of the more than 2 million U.S. soldiers deployed in Iraq or Afghanistan have experienced TBI.“In the military population we studied, patients with TBI have more alterations, sometimes called ‘potholes,’ in the white matter of their brains than patients without a history of TBI,” said senior study author Ricardo Jorge, M.D., UI professor of psychiatry.“The more severe the injury, the more white matter abnormalities occur. There is also a correlation between increased numbers of potholes and increased severity of cognitive alterations in executive functions — the ability to make a plan or a decision, for example.”The researchers note that, despite its prevalence, diagnosing mild TBI is difficult. They often have to rely on a patient’s recollection of a possible past head injury.In addition, symptoms of mild TBI tend to be wide-ranging and non-specific, including problems with vision, hearing, balance, emotions, and thinking, researchers said, noting there are few tools available to identify the condition or monitor the brain’s recovery or deterioration.Jorge and his research team used an MRI-based brain-scanning technique called diffusion tensor imaging (DTI) to study the brains of 72 veterans with mild TBI and 21 veterans without mild TBI.DTI measures the diffusion of water along the thin fibers known as axons that form connections between brain cells. When axons are intact, water flow follows the axon boundaries and has a well-defined direction, researchers explained.When the axon is damaged, water diffuses in many directions, a situation referred to as low fractional anisotropy. ”Decreased directionality of the water diffusion is a measure of lower integrity in the white matter,” Jorge said.Analysis of the DTI data allowed the researchers to detect areas of lower integrity in the patients’ white matter even though these potholes are scattered randomly throughout the brain and occur in different places in different patients.Veterans with mild TBI had significantly more potholes than veterans without TBI, the researchers report. The difference was not influenced by age, time since trauma, a history of mild TBI unrelated to deployment, or coexisting psychological problems like depression, anxiety, or post-traumatic stress disorder (PTSD).The number of potholes did, however, correlate with poorer performance on cognitive tests measuring decision-making and planning skills, the researchers noted.The team also examined the brains of civilians with non-combat-related mild TBI who were assessed early after the injury. The researchers found that these patients have even more white matter potholes than the military group.Although the results suggest that DTI measurements might hold promise as a tool for detecting and tracking mild TBI, Jorge cautioned that the current study is not large or specific enough to confirm that DTI-detected potholes are a biomarker for TBI brain damage.“To establish if this DTI approach is a useful technique for diagnosing mild TBI, we need to replicate these findings in a larger study and with patients who have mild TBI from other causes,” he said.The study was published online in the American Journal of Psychiatry.Source: University of Iowa Health Care